The present invention relates to torque overload clutches, and more particularly to automatic torque overload clutches providing consistent torque overload protection.
Torque overload clutches are used in various applications to generally limit the maximum level of torque transferred between two or more devices that are coupled to the clutch, such as a drive shaft and a driven shaft. When the amount of torque being transferred through the clutch exceeds a set level, the clutch allows for relative rotation between the devices to minimize any undesirable consequences associated with excess torque transfer. Some torque overload clutches provide for automatic re-coupling of the devices when the level of torque being applied to the clutch drops below the set maximum level.
In many mechanically actuated clutches, the maximum level of torque transmission is pre-set by selecting a biasing force that urges a moveable member into a coupling arrangement, wherein the entire clutch rotates in unison to transfer substantially all of the applied torque. Excessive torque applied to the clutch provides sufficient force to overcome the biasing force thus moving the moveable member to decouple the devices, for example, decoupling the drive shaft and the driven shaft such that they do not rotate in unison.
Consistent torque overload protection is beneficial in many applications. For instance, if the clutch decouples at a torque that is too low, the overall configuration may decouple prematurely thereby hampering effective operation of the devices. Alternatively, if the clutch decouples at a torque that is too high, the additional stresses may negatively impact the operational life of the devices. Take for example a wood chipper. A torque overload clutch may be coupled between the drive shaft of a motor and a roller feeding wood into a wood chute to be chipped. If the clutch decouples at too low of a torque value, the roller will not be able to feed wood up to the maximum capacity of the wood chipper. Conversely, if the clutch decouples at too high of a torque value, the motor (and any intermediate gearing) is subjected to excess, undesirable stress. It is desirable that the statistical range of torques at which a series of manufactured torque overload clutches disengage is within as narrow of a range as possible so that machines using them can be adjusted to operate predictably to their maximum capacity.
Many other applications benefit from consistent torque overload protection. Therefore, a need exists for an improved torque overload clutch that provides for consistent torque overload protection.